code: def check_reserved_words(graph):
      RESERVED = {"name", "next", "input", "index", "cmd"}
      msg = (
          "Step name *%s* is a reserved word. Choose another name for the "
          "step."
      )
      for node in graph:
          if node.name in RESERVED:
              raise LintWarn(msg % node.name)
  
imports: import re
  from .exception import MetaflowException
  from .util import all_equal
label_desc: Use image node_id 1 for calling a global function with example usage: check_reserved_words(graph) without return types